Method of forming disk phonograph records



Dec. 3, 1929. A. DE l.. SMITH 1,737,619

METHOD 0F FORMING DISK PHONOGRAPH RECORDS Filed Aug. 21. 1926 3 Sheets-Sheet 1 3,1929'. A DELSMITH f 1,737,619'

HETHQDUF FORMING DISK PHONOGRAPH RECORDS- Filed-Aug. 21. 192e arsneetsfsneetb 2 i Faq E5.V

TQRNE ii INVENToR. I

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klamm Dec. 3, 1929. A. DE L. SMITH METHOD OF FORMING DISK PHONOGRAPH RECORDS Filed Aug. 21. 192e D s sheets-sheet 5 I I INVENTOR. I l y @wld BY.

v ATTORNEY- Patented Dec. 3, 41929 ANNESLEY DE LOS SMITH, F NEW YORK, N. Y., ASISIGNOR T0 CAMEO RECQRD (IOR-l PORATION, 0F NEW YORK, N. Y.,

A CORPORATION 0F NEWT YORK METHOD OF FORMING DISK PHONOGRAPH RECORDS Application ledvvAugust 21, 1926. Serial No.v 130,597.

My present invention provides certain improvenlents in disk phonographrecords, and

also improvements in the method of making such records whereby certain objectionable features in the present manufacturing process will be eliminated. .Y

One of the principal objects of the invention is to provide an improved arrangement of the parts of the stamping dies whereby the making of such records isnot only greatly facilitated, but which are so constructed that they resist wear and are therefore capable of being used constantly for long periods.

Heretofore it has been the practice in as-H semblying the elements of the dies to so arrange the ring and stamper that there was present between their meeting faces a small vertical shoulder. When the two complementary dies were compressed some of the plastic material, of which the records are formed, was forced into the crevice between said shoulder and frequently became lsealed therein. This often necessitated 'prying a record from the die,- always a time-'consuming procedure and sometimes desctructive of the record. Eventually the edges' of the meeting faces of the elements due to the tremendous pressure imposed upon `them became worn and new die elements had to bev substituted. This wearing o' of the edges was evidenced a rim or slightlyA raised edge formed around the periphery of the disk. By my improved construction and arrangement of the die elements, I have beenable to extend the life of the parts greatly beyond their old tenure, and to increase the daily production of records from a given set of dies.

I haveffound that ify the' vertical shoulder at the meet-ing faces ofthe elements is eliminated and the overlapping of the ring and stamper occurs on a slight incline t0 the plane of the disk none of the plastic material will enter -between the parts. i' This is explainedvby the fact'that the pressure put upon the die elements brings the faces closely together at each stamping operation, thus opposing any tendency of the plastic material to force the underlyingv edge of the stamper away from the overlapping edge of 'the ring. i 1

I have found also that if the faces of the die elements forming the periphery of a rec.

ord are curved'so as to form a bead on the edge of the record, .that the record may be strippedF from the die much more readily, the enlarged edge thus formed Aobviating any tendency to create angular corners in the die 'during its use in which the plastic material may exhibit a tendency to adhere.

It has been the practice heretofore toV break off the fini around the disk by hand or otherwise, an operation which leaves a ring of irregular and jagged edges which are buffed ofi'l by sandpaper. Sometimes, in

breaking ofi' the iin close to the disk, pieces of.'

the record were also chipped off necessitating vthe discarding ofthe record. The buing step is of course time-consuming and expensive in'that it, requires handling'a record several different times,. and in order to obviate this and attendant operatipns I have provided means for perforating the iin at its junction with the disk for the dual purpose of rendering the fin easily separable and also to provide an edge on the finished record `which obviates the burnishing operation.

The improved construction above described is illustrated .in the-accompanying drawings which presentv one embodiment of myinvention, but Vit is to 'be understood that the invention is not limited to the specific structure therein shown, since it will occur to anyone in the art that modifications may be made thereof which will. not depart from the principles enunciated herein. A

In the drawings: Fig. 1 is a plan view of one of a pair of cooperating dies; Fig. 2 is a cross-section on thel hne 2"- x of Fig. 1. showing two cooperating dies 1n operatve position and a record being molded between them; A Fig'. 3 is an enlarged View of part of Fig. 2;

Fig. 4 is a cross-sectional view of a record edging faces of the rings;

Figs. 6 and 7 are edge and plan views of fragments of a record'illustrating the knurl- In order to make clear how the defects occurred in the present practice of making disk phonograph records, reference is first made to Figs. l() and 11, showing the die block a,

edging rings Zi and stamper c, between which the disk (Z is formed. The edging faces g of the rings Z) are beveled slightly and have small shoulders c overlying 'the edges e of the stampers vas shown. 'The rings extend beyond the edges ofthe stampers c and their bottoms are seated in the blocks a. In forming these seats a clearance of approximately four thousandths of an inch is providedeinitially so that when the rings are positioned and are forced into engagement with their seats the over-hanging shoulders will compress the edge f faces of the stampers forming slight indentatending to4 crowd them against the stampersl intime be separated an appreciable distance v tiols therein and effect a close union therew1 Hydraulic pressure is used in pressing the dies together, varying from fifty to seventy f1ve tons, which is exerted on the enclosed plastic material d and as this must in volume be slightly in excess of the space enclosed, 1n order to assure that the die will be Acompletely filled, it follows that a considerable pressure will be directed laterally against the.

projecting inclined surfaces g of the rings as theseapproach each other and the excess material is forced outwardly between them.`

This pressure repeatedly applied tends to spring the rings in places tending to openl the ]o1nt bet-Ween the shoulder and its point of engagement with the edge of the stamper.-

Likewise the repeated pressure on the rings and to force the latter against theblocks a results 1n t1me in a tendency to crush down n the edge of the block a immediately under the edge of the stamper, so that the latter will from the overlyingl shoulder of the ring. The last mentloned effect may also result if there 1s a s hght variation in forming'` `the depths of the ring seats, or in the accuracy of the rings themselves, or it may be due to inequalities occurring in the loss of temper in the rings. Irrespectlve of the immediate cause of the separation of the ring shoulder and the edge of the stamper it will be seen that at the point or points where the crevice (f Fig. 11) occurs, vthe plastic material will be forced in and repeated operations will serve to aggra`v vate or increase the amount of separation. A comparatively slight crevice will hold enough of the plastic material to render re-` moval of a disk impossible without rupturing it. Under such conditions when a record is removed, the crevice is filled with the plastic material which hardens and renders the corncr edges of succeeding records rough. As more and more records are made the wear upon these edges of the rings Aand stampers increases until they become worn to such an extent that the record comes ofi' the die with a slightly raised edge Eventually, of course, the edging rings and stampers must be discarded and replaced with new elements. This is wasteful, since the original stampers, so far as their face portions are concerned, are quite capable of further use.

By a reconstruction and rearrangement of the elements, I have been able to overcome this objectionable feature and to increase the In this improved form of die, the outer edge of the stamper c has an inclined flange y' and a curvedbead 7c adjoining it. Theedging ring is similarly curved at its inner face Z to form with the bead an arc of a circle. When these elements are assembled they will impart to the edgeof the disk a bead lml which issubstantially' circular in cross-section.

Curving the edging faces of the rings .and the stampers has more than esthetic value. In addition to diminishing the tendency of the record to stick to the die, it directs some of the lines of pressure ta-ngentially to the curva ture of the bead and thus assists in causing the plast-ic material to flow outwardly between the edging rings. Theoretically, the

by hand after Ythe record is removed from the l dies. f

To facilitate this operation and leave the edge of the record sufficiently smooth so that it need'not be subsequently burnished at its edge, the dies are formed in such a manner Y that as the last of the extruded material passes through the constantly narrowing slit between the dies it Will be rendered into a thin sheet or fin possessing irregularities in its contour. To thisend I provide the inner surfaces of the edging rings with a continution displaces a portion of the, metal, forming alternate depressions and lands, and this` displacement causes corresponding points to be struck upon the cutting edge n. of the ring so that this is correspondingly roughened or provided with a series of very line needle points. ,In other words, the material as it is extravasated will, at alternate points along the edge of the record, pile up in minute ridges and minute depressions effecting the fracturing margin which facilitates the re,- moval ofthe fin.

In the formation` of a record disk by means of the instrumentalities described, it will be seen that as the similarly formed upper and lower dies approach eachother, that the major portion of any excess plastic molding material will be forced outwardly between the cooperating edges of the ring dies and that the final portion of such excess which is extruded under the heavy hydra ulie pressure to which the dies are subjected as they approach each other, and which material 1s 11n-- mediately adjacent the edge of the record, will be forced between the aforementioned needle points. Therefore the line of attachment between the extended tin and the comparatively thick edge 'of the disk will be more or less wavy in appearance. These small waves or wrinkles occur at both sides of the fin and at some places the bottoms of certain waves at one side will nearly if not quite meet the bottom of the waves formed at the other side.- It has been found in practice that the resulting formation ofthe fin at its point of juncture With'the record greatly facilitates the removal of the fin when the record is removed `from the dies,whether this operation is performed while-the fin and record is stillheated or if the parts are allowed to cool. The increased ease with which the fin is removed while still warm, I attribute to a change in temperature occurring imn'iediate# ly upon the opening of the dies which occurs in the thinner` area where the wavy formation occurs.

Detachment of then is actually accomthe knurled or serrated edge than heretofore where therecord was bul'ed, smooth.

It will be seen that by arranging the meeting shoulders of the die elements at an inclination so as to overlap one another in their assembly any tendency for the plastic material to enter the joint between the rings and the stamper will be opposed by thc force imposed upon the flange j, which force is almost' at. right angles to the inclination of the face Z.

In addition to the parts described cach ol the molding dies comprises a. central locking bolt p, which is circular in cross-section and is provided with a screw s which is received in a threaded aperture in the die block a. The top of the bolt is flared at t and rests vupon the'beveled internal perij'ihery u, of the 4stamper c. Provision 1s made in the Way of a polygonal aperture v in the center of the bolt for receiving a tool by which the. bolt iS to be screwed into and out of the die. The bolts have raised portions w which meet to form a central aperture at the center of thev record.

In addition to the outer bead m, each stamper may also be provided with a circula r concentric ridge or ridges 11, r, and the center r i bolts may also have snnllar grooves y. fno

disks, it will be seen, are consequently formed with a plurality of circular ridges or elevations which, being spaced alike on all disks.

the other elevated rings, the music lines are protected against injury when the disk is laid upon a fiat surface and in handling the disks, particularly during the periods of inspection and packing and after they are taken off the press. For instance, in the latter operation it is not necessary to separate successive disks with sheets of paper. The internal beads or elevated rings cooperate with the enlarged rim to keep the centers of the disks from sagging when a number of them are stacked together. Theknurled or serrated .edge which is curved in cross-section facilitates picking up therecord and from a manufacturing viewpoint contributes `to a reduction in cost, as it is accepted as a finished product by the purchaser and minute particles adhering to the record that may be overlooked during inspection either pass unnoticed or vare ,easily brushed off or wiped off by the fingers.

In accordance with the provisions of the patent statutes the principle of the invention has been described, and illustrated by the portrayal of a structure which in practice has proved to be a satisfactory embodiment thereof, but it is desired to have it understood that the struetureshown is merely illustrative, and the invention may be ear.- ried out in other ways. y

Having described my invention, what I claim is:

1. The method of forming disk phonograph records consisting in compressing a massof molding material between dies having edges which substantially meet to form the periphery of the record and are serrated to give the edge of the record between its two ta'ces indentations, the points formed bythe serrations in one die cooperating with similar points formed on thel other die, and forming in the extruded web successively l weakened points of attachment between it and the record proper. i

2. The method of moldlng disk phonograph records consisting 1n compressing a mass of molding material between dies having knurled areal borders, the resulting rough cutting edges of which when substantially meeting to form the periphery of the record create weakened points of attachment or' the extruded web to the record.

3. The method of forming disk phonograph records consisting in compressing a mass of molding material between dies having edges which substantially meet to form the periphery of the record and are serrated to give the circumferential edge of the reeord small indentations, the points between the latter serving to forman area of weakness between the web of material extruded and the edge ofthe molded disk.

4. The method of molding disk phono- Y graph records consisting in compressing a mass of molding material between dies having knurled areal borders which forml altei-nate depressions and lands in the two half edges ofv the periphery of the molded record, and the serrated edges of which when substantially meeting form areas of weakness in the excess material extruded between said dies.

' 5. The method of forming disk phonograph records consisting in compressing a mass of molding material between die surfaces one of which at least has a raised surrounding edge formed with spaced depressions forming intervening points which cooperate with the other side to form areas of Weakness in .the material extruded between said dies.

This specification signed and witnessed this 10th day of' August, 1926.

ANNESLEY DE LOS SMITH. 

